import java.util.Scanner;

public class Test {
    public static int fib(int n){
        if (n <= 2){
        }
        int f1 = 1;
        int f2 = 1;
        int f3 = 0;
        for (int i = 3; i <= n; i++) {
            f3 = f1 + f2;
            f1 = f2;
            f2 = f3;
        }
        return f3;
    }
    public static void main(String[] args) {
       while (true){
           System.out.println("请输入：");
           Scanner scanner = new Scanner(System.in);
           int n = scanner.nextInt();
           int ret = fib(n);
           System.out.println(ret);
       }
    }
}
